<template>
    <canvas id="canvas" ></canvas>
</template>

<script>
export default {
  data() {
    return {
    };
  },
  mounted() {
    this.initCanvas();
  },
  methods: {
    initCanvas() {
      var num = 200;
      var w = window.innerWidth;
      var h = window.innerHeight;
      var max = 100;
      var _x = 0;
      var _y = 0;
      var _z = 150;
      var dtr = function(d) {
        return d * Math.PI / 180;
      };
      var rnd = function() {
        return Math.sin(Math.floor(Math.random() * 360) * Math.PI / 180);
      };
      var dist = function(p1, p2, p3) {
        return Math.sqrt(Math.pow(p2.x - p1.x, 2) + Math.pow(p2.y - p1.y, 2) + Math.pow(p2.z - p1.z, 2));
      };
      var cam = {
        obj: {
          x: _x,
          y: _y,
          z: _z
        },
        dest: {
          x: 0,
          y: 0,
          z: 1
        },
        dist: {
          x: 0,
          y: 0,
          z: 200
        },
        ang: {
          cplane: 0,
          splane: 0,
          ctheta: 0,
          stheta: 0
        },
        zoom: 1,
        disp: {
          x: w / 2,
          y: h / 2,
          z: 0
        },
        upd: function() {
          cam.dist.x = cam.dest.x - cam.obj.x;
          cam.dist.y = cam.dest.y - cam.obj.y;
          cam.dist.z = cam.dest.z - cam.obj.z;
          cam.ang.cplane = -cam.dist.z / Math.sqrt(cam.dist.x * cam.dist.x + cam.dist.z * cam.dist.z);
          cam.ang.splane = cam.dist.x / Math.sqrt(cam.dist.x * cam.dist.x + cam.dist.z * cam.dist.z);
          cam.ang.ctheta = Math.sqrt(cam.dist.x * cam.dist.x + cam.dist.z * cam.dist.z) / Math.sqrt(cam.dist.x * cam.dist.x + cam.dist.y * cam.dist.y + cam.dist.z * cam.dist.z);
          cam.ang.stheta = -cam.dist.y / Math.sqrt(cam.dist.x * cam.dist.x + cam.dist.y * cam.dist.y + cam.dist.z * cam.dist.z);
        }
      };
      var trans = {
        parts: {
          sz: function(p, sz) {
            return {
              x: p.x * sz.x,
              y: p.y * sz.y,
              z: p.z * sz.z
            };
          },
          rot: {
            x: function(p, rot) {
              return {
                x: p.x,
                y: p.y * Math.cos(dtr(rot.x)) - p.z * Math.sin(dtr(rot.x)),
                z: p.y * Math.sin(dtr(rot.x)) + p.z * Math.cos(dtr(rot.x))
              };
            },
            y: function(p, rot) {
              return {
                x: p.x * Math.cos(dtr(rot.y)) + p.z * Math.sin(dtr(rot.y)),
                y: p.y,
                z: -p.x * Math.sin(dtr(rot.y)) + p.z * Math.cos(dtr(rot.y))
              };
            },
            z: function(p, rot) {
              return {
                x: p.x * Math.cos(dtr(rot.z)) - p.y * Math.sin(dtr(rot.z)),
                y: p.x * Math.sin(dtr(rot.z)) + p.y * Math.cos(dtr(rot.z)),
                z: p.z
              };
            }
          },
          pos: function(p, pos) {
            return {
              x: p.x + pos.x,
              y: p.y + pos.y,
              z: p.z + pos.z
            };
          }
        },
        pov: {
          plane: function(p) {
            return {
              x: p.x * cam.ang.cplane + p.z * cam.ang.splane,
              y: p.y,
              z: p.x * -cam.ang.splane + p.z * cam.ang.cplane
            };
          },
          theta: function(p) {
            return {
              x: p.x,
              y: p.y * cam.ang.ctheta - p.z * cam.ang.stheta,
              z: p.y * cam.ang.stheta + p.z * cam.ang.ctheta
            };
          },
          set: function(p) {
            return {
              x: p.x - cam.obj.x,
              y: p.y - cam.obj.y,
              z: p.z - cam.obj.z
            };
          }
        },
        persp: function(p) {
          return {
            x: p.x * cam.dist.z / p.z * cam.zoom,
            y: p.y * cam.dist.z / p.z * cam.zoom,
            z: p.z * cam.zoom,
            p: cam.dist.z / p.z
          };
        },
        disp: function(p, disp) {
          return {
            x: p.x + disp.x,
            y: -p.y + disp.y,
            z: p.z + disp.z,
            p: p.p
          };
        },
        steps: function(_obj_, sz, rot, pos, disp) {
          var _args = trans.parts.sz(_obj_, sz);
          _args = trans.parts.rot.x(_args, rot);
          _args = trans.parts.rot.y(_args, rot);
          _args = trans.parts.rot.z(_args, rot);
          _args = trans.parts.pos(_args, pos);
          _args = trans.pov.plane(_args);
          _args = trans.pov.theta(_args);
          _args = trans.pov.set(_args);
          _args = trans.persp(_args);
          _args = trans.disp(_args, disp);
          return _args;
        }
      };
      (function() {
        "use strict";
        class threeD {
          constructor(param) {
            this.transIn = {};
            this.transOut = {};
            this.transIn.vtx = (param.vtx);
            this.transIn.sz = (param.sz);
            this.transIn.rot = (param.rot);
            this.transIn.pos = (param.pos);
          }
          vupd() {
            this.transOut = trans.steps(
            this.transIn.vtx,
            this.transIn.sz,
            this.transIn.rot,
            this.transIn.pos,
            cam.disp
            );
          }
        }
        class Build {
          constructor() {
            this.vel = 0.04;
            this.lim = 360;
            this.diff = 200;
            this.initPos = 100;
            this.toX = _x;
            this.toY = _y;
            this.go();
          }
          go() {
            this.canvas = document.getElementById("canvas");
            this.canvas.width = window.innerWidth;
            this.canvas.height = window.innerHeight;
            this.$ = canvas.getContext("2d");
            this.$.globalCompositeOperation = 'source-over';
            this.varr = [];
            this.dist = [];
            this.calc = [];
            for (var i = 0, len = num; i < len; i++) {
              this.add();
            }
            this.rotObj = {
              x: 0,
              y: 0,
              z: 0
            };
            this.objSz = {
              x: w / 5,
              y: h / 5,
              z: w / 5
            };
          }
          add() {
          this.varr.push(new threeD(
            {
              vtx: {
                x: rnd(),
                y: rnd(),
                z: rnd()
              },
              sz: {
                x: 0,
                y: 0,
                z: 0
              },
              rot: {
                x: 20,
                y: -20,
                z: 0
              },
              pos: {
                x: this.diff * Math.sin(360 * Math.random() * Math.PI / 180),
                y: this.diff * Math.sin(360 * Math.random() * Math.PI / 180),
                z: this.diff * Math.sin(360 * Math.random() * Math.PI / 180)
              }
            }
          ));
          this.calc.push( 
            {
              x: 360 * Math.random(),
              y: 360 * Math.random(),
              z: 360 * Math.random()
            }
          );
          }
          upd() {
            cam.obj.x += (this.toX - cam.obj.x) * 0.05;
            cam.obj.y += (this.toY - cam.obj.y) * 0.05;
          }
          draw() {
            this.$.clearRect(0, 0, this.canvas.width, this.canvas.height);
            cam.upd();
            this.rotObj.x += 0.1;
            this.rotObj.y += 0.1;
            this.rotObj.z += 0.1;
            for (var i = 0; i < this.varr.length; i++) {
              for (var val in this.calc[i]) {
                if (this.calc[i].hasOwnProperty(val)) {
                  this.calc[i][val] += this.vel;
                  if (this.calc[i][val] > this.lim)
                    this.calc[i][val] = 0;
                }
              }
              this.varr[i].transIn.pos = {
                x: this.diff * Math.cos(this.calc[i].x * Math.PI / 180),
                y: this.diff * Math.sin(this.calc[i].y * Math.PI / 180),
                z: this.diff * Math.sin(this.calc[i].z * Math.PI / 180)
              };
              this.varr[i].transIn.rot = this.rotObj;
              this.varr[i].transIn.sz = this.objSz;
              this.varr[i].vupd();
              if (this.varr[i].transOut.p < 0)
                continue;
              var g = this.$.createRadialGradient(this.varr[i].transOut.x, this.varr[i].transOut.y, this.varr[i].transOut.p, this.varr[i].transOut.x, this.varr[i].transOut.y, this.varr[i].transOut.p * 2);
              this.$.globalCompositeOperation = 'lighter';
              g.addColorStop(0, 'hsla(255, 255%, 255%, 1)');
              g.addColorStop(.5, 'hsla(' + (i + 2) + ',85%, 40%,1)');
              g.addColorStop(1, 'hsla(' + (i) + ',85%, 40%,.5)');
              this.$.fillStyle = g;
              this.$.beginPath();
              this.$.arc(this.varr[i].transOut.x, this.varr[i].transOut.y, this.varr[i].transOut.p * 2, 0, Math.PI * 2, false);
              this.$.fill();
              this.$.closePath();
            }
          }
          anim() {
            window.requestAnimationFrame = (function () {
              return window.requestAnimationFrame ||function (callback, element) {
                window.setTimeout(callback, 1000 / 60);
              };
            })();
            var anim = function () {
              this.upd();
              this.draw();
              window.requestAnimationFrame(anim);
            }.bind(this);
            window.requestAnimationFrame(anim);
          }
          run() {
            this.anim();
            window.addEventListener('mousemove', function (e) {
              this.toX = (e.clientX - this.canvas.width / 2) * -0.8;
              this.toY = (e.clientY - this.canvas.height / 2) * 0.8;
            }.bind(this));
            window.addEventListener('touchmove', function (e) {
              e.preventDefault();
              this.toX = (e.touches[0].clientX - this.canvas.width / 2) * -0.8;
              this.toY = (e.touches[0].clientY - this.canvas.height / 2) * 0.8;
            }.bind(this));
            window.addEventListener('mousedown', function (e) {
              for (var i = 0; i < 100; i++) {
                this.add();
              }
            }.bind(this));
            window.addEventListener('touchstart', function (e) {
              e.preventDefault();
              for (var i = 0; i < 100; i++) {
                this.add();
              }
            }.bind(this));
          }
        }
        var app = new Build();
        app.run();
      })();
      window.addEventListener('resize', function() {
        canvas.width = w = window.innerWidth;
        canvas.height = h = window.innerHeight;
      }, false);
    },
  },
};
</script>
<style scoped>
</style>
